drivers/input/touchscreen/ad7879-spi.c

   1 /*
   2  * AD7879/AD7889 touchscreen (SPI bus)
   3  *
   4  * Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/input.h>        /* BUS_SPI */
  10 #include <linux/pm.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/module.h>
  13
  14 #include "ad7879.h"
  15
  16 #define AD7879_DEVID            0x7A    /* AD7879/AD7889 */
  17
  18 #define MAX_SPI_FREQ_HZ      5000000
  19 #define AD7879_CMD_MAGIC     0xE000
  20 #define AD7879_CMD_READ      (1 << 10)
  21 #define AD7879_CMD(reg)      (AD7879_CMD_MAGIC | ((reg) & 0xF))
  22 #define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
  23 #define AD7879_READCMD(reg)  (AD7879_CMD(reg) | AD7879_CMD_READ)
  24
  25 #ifdef CONFIG_PM_SLEEP
  26 static int ad7879_spi_suspend(struct device *dev)
  27 {
  28         struct spi_device *spi = to_spi_device(dev);
  29         struct ad7879 *ts = spi_get_drvdata(spi);
  30
  31         ad7879_suspend(ts);
  32
  33         return 0;
  34 }
  35
  36 static int ad7879_spi_resume(struct device *dev)
  37 {
  38         struct spi_device *spi = to_spi_device(dev);
  39         struct ad7879 *ts = spi_get_drvdata(spi);
  40
  41         ad7879_resume(ts);
  42
  43         return 0;
  44 }
  45 #endif
  46
  47 static SIMPLE_DEV_PM_OPS(ad7879_spi_pm, ad7879_spi_suspend, ad7879_spi_resume);
  48
  49 /*
  50  * ad7879_read/write are only used for initial setup and for sysfs controls.
  51  * The main traffic is done in ad7879_collect().
  52  */
  53
  54 static int ad7879_spi_xfer(struct spi_device *spi,
  55                            u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
  56 {
  57         struct spi_message msg;
  58         struct spi_transfer *xfers;
  59         void *spi_data;
  60         u16 *command;
  61         u16 *_rx_buf = _rx_buf; /* shut gcc up */
  62         u8 idx;
  63         int ret;
  64
  65         xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
  66         if (!spi_data)
  67                 return -ENOMEM;
  68
  69         spi_message_init(&msg);
  70
  71         command = spi_data;
  72         command[0] = cmd;
  73         if (count == 1) {
  74                 /* ad7879_spi_{read,write} gave us buf on stack */
  75                 command[1] = *tx_buf;
  76                 tx_buf = &command[1];
  77                 _rx_buf = rx_buf;
  78                 rx_buf = &command[2];
  79         }
  80
  81         ++xfers;
  82         xfers[0].tx_buf = command;
  83         xfers[0].len = 2;
  84         spi_message_add_tail(&xfers[0], &msg);
  85         ++xfers;
  86
  87         for (idx = 0; idx < count; ++idx) {
  88                 if (rx_buf)
  89                         xfers[idx].rx_buf = &rx_buf[idx];
  90                 if (tx_buf)
  91                         xfers[idx].tx_buf = &tx_buf[idx];
  92                 xfers[idx].len = 2;
  93                 spi_message_add_tail(&xfers[idx], &msg);
  94         }
  95
  96         ret = spi_sync(spi, &msg);
  97
  98         if (count == 1)
  99                 _rx_buf[0] = command[2];
 100
 101         kfree(spi_data);
 102
 103         return ret;
 104 }
 105
 106 static int ad7879_spi_multi_read(struct device *dev,
 107                                  u8 first_reg, u8 count, u16 *buf)
 108 {
 109         struct spi_device *spi = to_spi_device(dev);
 110
 111         return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
 112 }
 113
 114 static int ad7879_spi_read(struct device *dev, u8 reg)
 115 {
 116         struct spi_device *spi = to_spi_device(dev);
 117         u16 ret, dummy;
 118
 119         return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
 120 }
 121
 122 static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
 123 {
 124         struct spi_device *spi = to_spi_device(dev);
 125         u16 dummy;
 126
 127         return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
 128 }
 129
 130 static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
 131         .bustype        = BUS_SPI,
 132         .read           = ad7879_spi_read,
 133         .multi_read     = ad7879_spi_multi_read,
 134         .write          = ad7879_spi_write,
 135 };
 136
 137 static int __devinit ad7879_spi_probe(struct spi_device *spi)
 138 {
 139         struct ad7879 *ts;
 140         int err;
 141
 142         /* don't exceed max specified SPI CLK frequency */
 143         if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
 144                 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
 145                 return -EINVAL;
 146         }
 147
 148         spi->bits_per_word = 16;
 149         err = spi_setup(spi);
 150         if (err) {
 151                 dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
 152                 return err;
 153         }
 154
 155         ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
 156         if (IS_ERR(ts))
 157                 return PTR_ERR(ts);
 158
 159         spi_set_drvdata(spi, ts);
 160
 161         return 0;
 162 }
 163
 164 static int __devexit ad7879_spi_remove(struct spi_device *spi)
 165 {
 166         struct ad7879 *ts = spi_get_drvdata(spi);
 167
 168         ad7879_remove(ts);
 169         spi_set_drvdata(spi, NULL);
 170
 171         return 0;
 172 }
 173
 174 static struct spi_driver ad7879_spi_driver = {
 175         .driver = {
 176                 .name   = "ad7879",
 177                 .bus    = &spi_bus_type,
 178                 .owner  = THIS_MODULE,
 179                 .pm     = &ad7879_spi_pm,
 180         },
 181         .probe          = ad7879_spi_probe,
 182         .remove         = __devexit_p(ad7879_spi_remove),
 183 };
 184
 185 static int __init ad7879_spi_init(void)
 186 {
 187         return spi_register_driver(&ad7879_spi_driver);
 188 }
 189 module_init(ad7879_spi_init);
 190
 191 static void __exit ad7879_spi_exit(void)
 192 {
 193         spi_unregister_driver(&ad7879_spi_driver);
 194 }
 195 module_exit(ad7879_spi_exit);
 196
 197 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 198 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
 199 MODULE_LICENSE("GPL");
 200 MODULE_ALIAS("spi:ad7879");